Wednesday, 4 September 2019

How to enter AT mode in HC-05 Bluetooth module

I will cover how to change password, name or mode (master or slave) in HC-05 Bluetooth module. 

Things required:

1. Arduino Uno board
2. Jumper wires
3. HC-05

1. Upload a blank program to your Arduino.

2. Make the following connections:

Arduino                              HC-05
TX              ====>             TX
RX              ====>             RX
VCC            ====>             VCC
GND           ====>              GND
HC-05 bluetooth module

3. Before powering up the Arduino, the little button on the HC-05 should be pressed and then released a few seconds after powering up the Arduino..  

4. The HC-05 in now in AT mode and its LED will blink approximately once every 2 seconds.

5. Open serial monitor in the Arduino program. The Baud rate should be selected to 38400 and both nl and cr should be selected.

6. Check some AT commands:

Type AT and press enter
The response should be OK

AT+ROLE? and press enter
The response is 0 or 1
0- Slave
1- Master

AT+UART? and press enter
The response is Baud rate

AT+PSWD? and press enter
The response is 1234    // that is the password.

For changing the password, command is AT+PSWD="1587"  
This command will set the password to 1587
Note: you need the quotation marks around the number selected.

There are other AT commands available at this link: 

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